A show-wood chair has a rule that upholstered chairs do not: everything is visible, so everything has to be finished.
On a fully upholstered chair the frame is a skeleton. Nobody sees the outer face of the back, so it is left rough-sawn, unfinished and often not even planed - there is no reason to work it, because cloth is going over it.
Here the frame is the design. The balloon is exposed on both faces, which means the carving on its outer edge has to be cut with the same care as the inner one, the mouldings have to run true where the eye can compare front to back, and the ebonising has to be built up in even layers on a surface that will be seen from behind at close range.
That doubles the carving on the back frame and it changes how the chair is made. The frame is carved, finished and completely done before a single tack goes in, because once upholstery is on there is no way to reach the inner edge of the balloon again.
It also means our carvers cannot hide a mistake. On an upholstered frame a poor cut disappears under the cover. On show wood, the only fix is to start the member again.